The present invention relates to an agent for improving processability of fibers. Generally, fibers are subjected to various treatments such as scouring, bleaching and dyeing to enhance commercial value thereof until they are processed into the final fibrous products. Various chemicals and dyes are used in the treatments. However, impurities contained in the fibers per se, impurities incorporated therein in the preceding steps and ions contained in hard water pose problems of inhibiting penetration of the chemicals into the fibers to cause a non-level finish and a rough hand. The present invention provides an agent for effecting the treatment of the fibers smoothly to obtain excellent results, i.e. an agent for improving processability of fibers.
Cellulose fibers have been scoured with an alkali, surfactant and solvent in the prior art. Particularly, a combination of an alkali with a surfactant has been employed widely. The cellulose fibers have been scoured for the purpose of removing water-repellent substances, i.e. primary impurities (natural impurities) such as greases and waxes and secondary impurities (additional impurities) such as machine oils from the fibers to impart wettability and water-absorbing properties to the fibers so that the penetration of the chemicals is facilitated and the operation is made easy in the subsequent steps of bleaching, dyeing and finishing the fibers. Thus, by this preliminary treatment, the commercial value of the product can be raised and the characteristic properties of the fibers can be exhibited. However, the scouring process wherein the combination of an alkali and a surfactant is used has problems to be solved as will be described below.
When water having a high hardness is used in the scouring, water-hardening components are bonded with fatty acids formed by the hydrolysis of the grease with the alkali to form a metallic soap. The metallic soap thus formed is deposited on the fibers to be scoured. The metallic soap which cannot be easily emulsified or dispersed by an ordinary scouring surfactant remains on the fibers still after completion of the scouring to make the fibers water-repellent. Consequently, the wettability and water-absorbing property required of the fibers are damaged and the chemicals cannot penetrate therein in the subsequent bleaching, dyeing and finishing steps to pose the problems. To solve these problems, ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, hydroxyethylenediaminetriacetic acid, nitrilotriacetic acid or sodium tripolyphosphate has been used but the effects of them are not always sufficient. Thus, no satisfactory measure has been developed as yet.
Silk fibers comprise generally fibroin and sericin surrounding the fibroin. To realize the essential properties of silk, it is necessary to remove sericin. Sericin has been removed by the scouring with a surfactant and an alkali. However, this process has problems to be solved as will be described below.
When water having a high hardness is used in the scouring of silk, ions in the hard water are bonded with a soap used as the surfactant to form a metallic soap which is difficultly soluble in water. The metallic soap is deposited on the silk fiber. Further, the ions in the hard water are bonded also with, for example, sodium silicate used as the alkali to form water-insoluble silicates, which are deposited on the silk fibers to worsen the hand thereof or to make the penetration of the chemicals difficult in the subsequent dyeing and finishing steps. Problems are thus caused. The scouring time of the silk is elongated by the soap to damage the silk fibers. To solve these problems, there has been used ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, hydroxyethylenediaminetriacetic acid, nitrilotriacetic acid or sodium tripolyphosphate but the effects of them are not always sufficient. Thus, no satisfactory measure has been developed yet.
Textiles of regenerated fibers such as rayon and cuprammonium rayon, semisynthetic fibers such as diacetate and triacetate fibers and synthetic fibers such as polyester, nylon and acrylic fibers contain secondary impurities such as a spinning oil, a sizing agent used for facilitating the twisting and weaving, a spin finish and dirts, although they do not contain the primary impurities that are present in natural cellulose fibers. These impurities must be removed completely or uniformly, since they worsen the hand of the fibers and inhibit the penetration of a dyeing liquid and resin solution in the dyeing and finishing steps to cause an unlevel dyeing or unlevel resin finish. The sizing agents include natural starch sizing agents such as potato starch and wheat starch sizing agents and synthetic sizing agents such as polyvinyl alcohol, acrylic acid polymers and vinyl acetate copolymers. Among them, the synthetic sizing agents, particularly, the acrylic acid polymers, have been used widely, since the natural starch sizing agents generally have an incomplete adhesion and they cannot be removed easily. To remove the impurities such as the spinning oil, sizing agent, lubricant and dirts, the scouring is effected generally using a surfactant and an alkali such as sodium hydroxide. However, this process has problems to be solved as will be described below.
When water having a high hardness is used in the scouring, components of the hard water are bonded with fatty acids formed by the hydrolysis of oil components in the lubricant with the alkali to form a water-insoluble metallic soap. The metallic soap thus formed is deposited on the fibers to be scoured. The metallic soap which cannot be easily emulsified or dispersed by an ordinary surfactant used in the scouring remains on the fibers after completion of the scouring. Consequently, the hand of the treated fibers becomes rough and the chemicals cannot easily penetrate therein in the subsequent dyeing and finishing steps to cause problems. Further, the acrylic acid polymers used as the synthetic sizing agent are bonded with the components of the hard water to form a water-insoluble sizing agent, which is deposited again on the fibers to be scoured to pose the same problems as described above. To solve these problems, there has been used ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, hydroxyethylenediaminetriacetic acid, nitrilotriacetic acid and sodium tripolyphosphate but their effects are not always sufficient. Thus, no satisfactory measure has been developed yet.
A specific phenomenon of polyester fibers has been known that they are hydrolyzed with a hot alkali solution and the surfaces are gradually dissolved to make the fibers thin. When textiles or knittings of the polyester fibers are subjected to this treatment, the gaps in the fibers are increased to make the textiles or knittings bulky, to loosen and soften the fibers and to realize a so-called silky hand. Though the polyester fibers are subjected to the alkali treatment frequently before the dyeing treatment, this process has problems as will be described below.
When water having a high hardness is used in the weight reduction with the alkali, components of the hard water are bonded with polyester oligomers formed in this treatment to form water-insoluble salts. The formed salts are deposited on the fibers to worsen the hand and to make the penetration of chemicals difficult in the subsequent steps. These defects are observed also in washing steps before and after a neutralization step following the step of weight reduction with alkali. To solve these problems, there have been used ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, hydroxyethylenediaminetriacetic acid, nitrilotriacetic acid and sodium tripolyphosphate but their effects are yet insufficient. Thus, no satisfactory measure has been developed as yet.
The cellulose fibers are bleached generally after the scouring to remove natural colorants remaining in the fibers and colorants attached thereto afterwards. The bleaching has been effected with a peroxide, chlorine or sodium chlorite. Among them, the peroxides have been employed widely in general, since they do not damage the fibers and durable whiteness can be realized by an easy operation. In the peroxide bleaching, colorants contained in the cellulose fibers are decomposed by oxidation with nascent oxygen formed by a decomposition of hydrogen peroxide. The oxidative decomposition is effected in the presence of an alkali such as sodium hydroxide, since a high efficiency can be obtained under alkaline conditions. Further, sodium silicate is used as a stabilizing agent in the hydrogen peroxide decomposition under the alkaline conditions. Therefore, the bleaching bath comprises hydrogen peroxide, an alkali (such as sodium hydroxide) and sodium silicate (having an SiO.sub.2 /Na.sub.2 O molar ratio of 2.5/1). When water having a high hardness is used in the bleaching, components of the hard water are bonded with sodium silicate to form water-insoluble silicates such as calcium silicate and magnesium silicate, which are deposited on the fibers. Consequently, the whiteness of the cloth cannot be improved, its hand is worsened and the coefficient of friction with a needle of a sewing machine is increased to cause troubles in the sewing. It has been demanded to overcome these defects. To solve these problems, there have been used ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, hydroxyethylenediaminetriacetic acid, nitrilotriacetic acid and sodium tripolyphosphate. However, their effects are still insufficient. Thus, no satisfactory measure has been developed yet.
Cellulose fibers are generally dyed with direct dyes, sulfide dyes, threne dyes, naphthol dyes, reactive dyes, basic dyes and acid dyes. These dyes have characteristic properties. Namely, the direct dyes dye fibers by physicochemical adsorption and the color fastness can be increased easily by a fixing treatment effected after the dyeing. The sulfide dyes exhibit an excellent color fastness (dyeing fastness) but the realized color has only a poor vividness. The threne dyes exhibit a quite excellent dyeing fastness. The naphthol dyes require complicated steps such as penetration of a grounder into the fiber and the development by diazotizing a developer, though they exhibit a relatively vivid color tone and a good dyeing fastness. The reactive dyes dye fibers by forming covalent bonds between the dye and the fibers to exhibit an excellent vividness and dyeing fastness. The basic dyes require a complicated mordanting step and exhibit a low dyeing fastness. The acid dyes require a complicated dyeing process and the resulting hue is unstable. Therefore, the direct dyes, threne dyes and reactive dyes have mainly been used among them. The direct dyes include various dyes, mainly metal-containing azo dyes. These metal-containing compounds are contained frequently also in the acid dyes and the reactive dyes. The metal-containing dyes comprise a metal atom such as chromium, copper, cobalt, iron or aluminum coordinated with a colorant molecule. However, in the dyeing with such dyes, problems which will be described below have been posed and the solution thereof has been demanded. When water having a high hardness is used, the components of the water inhibit the solubilization or dispersion of the dye to make the level dyeing impossible. For solving this problem, a chelating agent such as ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, hydroxyethylenediaminetriacetic acid or nitrilotriacetic acid has been used. Though the chelating agent captures the water-hardening components to some extent to exhibit a slight level-dyeing effect, the effect is still poor. In addition, the chelating agent forms a complex salt with the metal contained in the dye as the developing group. Consequently, the balance of the coordination between the dye and the metal is broken and the hue of the dyed cloth is far deviated from the intended hue. This is a fatal defect. The threne dyes which are important dyes in dyeing the cellulose fibers are water-insoluble dyes having two or more carbonyl groups. In dyeing with this dye, it is reduced with an alkali to convert the carbonyl groups into a leuco sodium salt which is water-soluble and has a high affinity with the cellulose fibers. After the dyeing with this dye, the leuco sodium salt is oxidized with an acid to form a quinone compound. Thus, the color development and water-insolubilization can be effected simultaneously. This process also has the following problem to be solved: when water having a high hardness is used in the dyeing, water-hardening components in the water used are bonded with the dye to form a dye dimer having no solubility in water nor affinity with the cellulose fibers. Therefore, a color depth expected from a dye concentration used cannot be obtained. For solving this problem, a chelating agent such as ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, hydroxyethylenediaminetriacetic acid or nitrilotriacetic acid has been used. However, their effects have been yet insufficient. Thus, no satisfactory measure has been developed as yet.
Generally, natural fibers such as silk and wool, regenerated fibers such as rayon and cuprammonium rayon, semisynthetic fibers such as cellulose diacetate and triacetate fibers and synthetic fibers such as polyester, nylon and acrylic fibers are dyed for the purpose of enhancing the commercial value and fashionability of the fibers.
The dyeing can be effected by various processes. For example, a dip dyeing in a batch system is effected by immersing a material to be dyed such as fiber, thread, textile, knitting, non-woven cloth or fibrous product in a dye bath to adsorb the dye on the material while the temperature and time are controlled. Various methods have been proposed for effecting the level dyeing in this process. For example, a dyeing assistant selected depending on the fiber and the dye is added to the dye bath. However, in this process, the dye is coagulated or precipitated in the dye bath to make the level dyeing impossible due to tarring or dyeing specks under some dyeing conditions or when water having a high hardness is used even when a levelling agent having a high dispersibility is used or even when a dispersing agent in addition to another dispersing agent contained already in the dye is used. A reduction clearing technique has been employed for improving the dyeing fastnesses by removing the non-fixed moiety of the dye. However, even when a dyeing assistant such as a levelling agent or dispersing agent is used in the dyeing, a considerable amount of the non-fixed dye remains on the surface of the fiber to reduce the reduction clearing properties. For solving this problem, an additive such as ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, hydroxyethylenediaminetriacetic acid, nitrilotriacetic acid or sodium tripolyphosphate is added to the dye bath. However, their effects have been yet insufficient. Thus, no drastic measure has been developed as yet.
In a continuous dyeing process such as a thermosol dyeing process or padding/steaming dyeing process, a material to be dyed such as textile, knitting or non-woven fabric is treated with a dye solution to effect the padding and then the color is developed by dry heating or steaming treatment. For effecting the level dyeing or increasing the utilization of the dye, a sizing agent and a dispersing agent selected suitably depending on the fibrous material and the dye are added to the dye bath. Under some dyeing conditions or when water having a high hardness is used, the dye is coagulated or precipitated to cause migration even in the presence of the dispersing agent or sizing agent. As a result, the level dyeing becomes impossible due to dyeing specks, etc. Some sizing agents are bonded with the hardening component contained in water to form an insoluble sizing agent which cannot be removed completely in a washing (desizing) step following the dyeing step. The similar problems, i.e. non-level dyeing and poor desizing effect, are posed also in a printing process such as direct printing, colored discharge or resist printing, or white discharge or resist printing wherein a sizing agent is used. To solve these problems, an additive such as ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, hydroxyethylenediaminetriacetic acid, nitrilotriacetic acid or sodium tripolyphosphate has been added to the dye bath. However, their effects have been yet insufficient. Thus, no satisfactory measure has been developed as yet.
After intensive investigations made for the purpose of solving the problems posed in processing the fibers, the inventors have found that the processability can be improved by using a specified compound. The present invention has been completed on the basis of this finding.